JP4022398B2 - Method and apparatus for creating phase shift mask - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention is used in a photolithography process in the manufacture of semiconductor integrated circuits, liquid crystal display devices, and the like.Method and apparatus for making a phase shift maskAbout.
[0002]
[Prior art]
  In a recording method in which an exposure pattern of an exposure mask is directly imaged on an exposure object by proximity exposure, lens projection exposure, mirror projection exposure, etc., resolution of the exposure pattern having a line width comparable to the wavelength of exposure light In order to eliminate the inconvenience that is difficult due to the light diffraction phenomenon (so-called diffraction limit), there is a recording method using a phase shift mask having a phase modulation layer called a phase shifter.
[0003]
  In such a recording method using a phase shift mask, for example, a phase shifter is formed on one of two approaching light transmission parts formed on the phase shift mask, and the phases of light transmitted through both light transmission parts are mutually different. If they are reversed, diffracted light beams that interfere with each other in opposite phases cancel each other, so that the diffraction limit is relaxed and the resolution of image formation on the object to be exposed is improved.
[0004]
  However, since the recording method using the phase shift mask uses a lens optical system as the imaging optical system, the aberration and numerical aperture of the lens optical system have an effect on the imaging resolution. The resolution of the resulting image was limited.
[0005]
  In order to eliminate the inconvenience that the resolution of imaging is limited due to the aberration and numerical aperture of the imaging lens optical system, interference fringes including information on the exposure pattern of the phase shift mask were formed. Using the hologram mask, the hologram mask is irradiated with laser light, and the light having passed through the interference fringes of the hologram mask is imaged on the object to be exposed, whereby a pattern having the exposure pattern information of the phase shift mask is applied to the object to be exposed. There is a method of forming.
[0006]
  In such a recording method using a hologram mask, in principle, an image having no aberration can be obtained regardless of whether or not an optical system such as a lens is provided between the hologram mask and an object to be exposed. At the same time, since a high numerical aperture (NA) is easily obtained, high-resolution imaging can be obtained.
[0007]
[Problems to be solved by the invention]
  However, the production of the hologram mask is performed by recording the information of the phase shift mask serving as the original plate on the hologram material, which has the problem that the production of the phase shift mask is difficult.
[0008]
  An object of the present invention is to make it easy to record information on a phase shift mask on a hologram material in the production of a hologram mask.
[0009]
[Solution means, actions and effects for solving the problems]
  A method for producing a phase shift mask according to the present invention is a method for producing a phase shift mask having phase modulation information including at least two types of phase value regions, and includes at least two types corresponding to the phase value regions. A step of providing an original mask; a first object beam irradiated on the hologram material through the first original mask; and a first reference beam irradiated on the hologram material without passing through the first original mask. The first exposure step of exposing the hologram material to the light transmission shielding pattern of the first original mask, and the second object light irradiated to the hologram material through the second original mask And the second reference light irradiated to the hologram material without passing through the second original mask, the light transmission shielding pattern of the second original mask is exposed to the hologram material. A second exposure step, comprising: a first phase difference between the first object light and the first reference light; and a second phase difference between the second object light and the second reference light. The second phase difference is different.
[0010]
  Other according to the present inventionFabrication of phase shift maskThe method isA method of creating a phase shift mask having phase modulation information including at least two types of phase value regions, comprising: preparing at least a first original mask and a second original mask corresponding to each phase value region When,Using the first object light irradiated on the hologram material through the first original mask and the first reference light irradiated on the hologram material without passing through the first original mask, 1 original maskLight ofA first exposure step of exposing the holographic material to the transmissive shielding pattern;FirstThe second object light applied to the hologram material through the original mask of 2 and the second reference light applied to the hologram material without passing through the second original mask are used to emit the light from the light source. At any position on the optical path to the hologram material, the first phase difference between the first object light and the first reference light, the second object light, and the second reference light A second exposure step of changing the second phase difference so as to be different from the second phase difference between and exposing the light transmission shielding pattern of the second original mask to the hologram material. .
[0011]
  like thatFabrication of phase shift maskAccording to the method, the information recorded on the hologram material in the first exposure step includes information on the light transmission shielding pattern of the first original mask, and the information recorded on the hologram material in the second exposure step is second. Information on the light transmission shielding pattern of the original mask and modulation information on the phase.
[0012]
  For example, the light transmission shielding pattern of the exposure pattern of the phase shift mask is appropriately assigned to the first original mask and the second original mask, and corresponds to the phase modulation information of the phase shifter of the phase shift mask in the second exposure step. If the second phase difference is changed as described above, the information recorded on the hologram material in the first exposure step and the information recorded on the hologram material in the second exposure step and including modulation information relating to the phase are 2 It is recorded on the hologram material by one exposure.
[0013]
  Since the pattern including the phase difference of the target phase shift mask is assigned to the first original mask and the second original mask as a light transmission shielding pattern, it is necessary as compared with the case where the target phase shift mask is used as the original. The number of original masks increases, but the phase shift maskEasy to make.
[0014]
  The first exposure step and the second exposure step may be a second exposure step following the first exposure step.
[0015]
  The reference light in the first exposure step and the second exposure step may be generated by the same reference light optical system.
[0016]
  The phase modulation information of the phase shift mask may have two types of phase values different from each other by π.
[0017]
  The step of changing the phase difference preferably includes at least an optical path from the light source through the second original mask to the hologram material and an optical path from the light source to the hologram material without passing through the second original mask. A step of changing one of the optical path lengths may be provided. In the step of changing the phase difference, the phase of the light whose optical path length is changed is modulated, and the second phase difference is changed.
[0018]
  The light transmission shielding pattern is a strip-shaped light transmission portion having a predetermined width dimension, a plurality of light transmission portions arranged in a striped pattern, and a plurality of strip-shaped light transmission portions arranged between the plurality of light transmission portions. A pattern including a light shielding portion, wherein the light transmitting portion of the first original mask corresponds to at least a part of a region shielded by the light shielding portion of the second original mask, The difference between the phase difference of 1 and the second phase difference may be approximately π. As a result, information on a pattern having a spatial frequency reduced by a plurality of strip-shaped light transmitting portions and light shielding portions alternately arranged in a striped pattern and information on two waves in opposite phases are obtained. Recorded on hologram material. Such a phase shift mask is generally called “Shibuya Levenson type”.
[0019]
  Further, between the diffraction efficiency due to the first interference fringes formed on the hologram material in the first exposure step and the diffraction efficiency due to the second interference fringes formed on the hologram material in the second exposure step. There may be included a diffraction efficiency changing step for causing a difference in the above. By the exposure method including such a diffraction efficiency changing step, it is possible to produce a hologram mask having the same function as the function of the phase-shift mask light semi-transparent phase shifter. Such a phase shift mask is generally called a “halftone type”.
[0020]
  The diffraction efficiency changing step reduces the light intensity of the object light with respect to the reference light on the light source side from the original mask so that the light intensity ratio of the object light is smaller than a light intensity ratio necessary to maximize the diffraction efficiency. Alternatively, an exposure amount adjusting step may be provided in which an exposure amount given to the hologram material is adjusted to be smaller than an exposure amount necessary to maximize the diffraction efficiency. A hologram mask having the same function as that of the phase shifter having various light transmittances of the phase shift mask is manufactured by the exposure method including the diffraction efficiency changing step including the light intensity reducing step or the exposure amount adjusting step. can do.
[0021]
  The hologram material may be formed with the same photosensitive film or photosensitive layer used in both the first exposure step and the second exposure step, or the first exposure step and the second exposure step. Different photosensitive films or photosensitive layers used for each of the exposure steps may be formed.
[0022]
  An apparatus for producing a phase shift mask according to the present invention is an apparatus for producing a phase shift mask for producing a phase shift mask having phase modulation information, and a light source,An optical system of object light in which light from the light source enters the hologram material as object light having passed through the original mask, and reference light in which the light from the light source enters the hologram material as reference light without passing through the original mask. An optical system; and phase modulation means provided in at least one of the object light optical system and the reference light optical system.
[0023]
  like thatFabrication of phase shift maskAccording to the apparatus, the information recorded on the hologram material by the first exposure includes information on the light transmission shielding pattern of the first original mask, and the information recorded on the hologram material by the second exposure is the second original plate. It includes information on the light transmission shielding pattern of the mask and modulation information on the phase.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
  With reference to FIG.Phase shift mask or hologram mask manufacturing apparatusAn exposure apparatus will be described. The exposure apparatus shown in FIG. 1 is an example of an exposure apparatus for producing a hologram mask, and other exposure apparatuses may be used.
[0025]
  In FIG. 1, an exposure apparatus 10 includes a light source 12, a condensing optical system 24 that focuses light 16 guided from the light source 12 and passed through an original mask 14 onto a photosensitive material 20 of a hologram mask 18 as object light 22, and a light source 12. And a reference light forming optical system 30 for guiding the light 26 as the reference light 28 to the photosensitive material 20 without passing through the original mask 14.
[0026]
  As the light source 12, a laser having coherence, for example, various lasers such as an Ar laser, a Kr laser, and a YAG laser can be used.
[0027]
  The original mask 14 includes a light transmissive mask substrate, and a light modulation layer having a light transmissive portion and a light shielding portion formed on the mask substrate. The mask substrate is made of a glass material having excellent light transmission properties such as quartz glass. The light shielding part is formed of a metal thin film by thin film technology. In the embodiment of FIG. 1, chromium is used as the material for the metal thin film.
[0028]
  As the photosensitive material 20, a material that can be recorded as hologram information can be used, for example, silver salt photosensitive material, dichroate gelatin, US EI DuPont de Nemours and Company (EI). Photopolymer for holograms (for example, trade name Omnidex) manufactured by Dupont de Nemours & Company) can be used.
[0029]
  Further, the exposure apparatus 10 includes a phase modulation device 32 disposed in an optical path from the light source 12 through the original mask 14 to the photosensitive material 20 of the hologram mask 18. The phase modulation device 32 changes the optical path length of one of the lights 36 and 38 obtained by dividing the light 26 from the light source 12 by the beam splitter 34. Thereby, as a result, the phase difference between the object beam 22 and the reference beam 28 is changed.
[0030]
  The phase modulation apparatus shown in FIG. 2 is two typical examples, and other phase modulation apparatuses may be used. The phase modulation device 32 shown in FIG. 2A includes a first reflection mirror 54, a corner cube 56, and a second reflection mirror 58.
[0031]
  The corner cube 56 has three reflecting surfaces 60, 62, and 64 that are perpendicular to each other, and is formed such that light 66 incident on the corner cube 56 and light 68 emitted from the corner cube 56 are parallel to each other. The corner cube 56 is moved in the direction of the arrow 70 by a driving device (not shown) and adjusted in position.
[0032]
  Light 38 guided from the light source 12 (see FIG. 1) enters the phase modulation device 32, is reflected by the first reflection mirror 54, and enters the corner cube 56 as light 66. The light that has entered the corner cube 56 is sequentially reflected by the reflecting surfaces 60, 62, and 64, and is emitted from the corner cube 56 as light 68. The light 68 travels in the opposite direction parallel to the light 68 incident on the corner cube 56, is reflected by the second reflecting mirror 58, and exits the phase modulator 32 as light 72.
[0033]
  By moving the corner cube 56 in the direction of the arrow 70, the optical path length through which the light 38 passes through the phase modulator 32 can be arbitrarily adjusted.
[0034]
  The phase modulation device 32 shown in FIG.₀A light transmissive member 74 having The light transmitting member 74 has surfaces 76, 78, 80, 82, and 84 that change the thickness dimension in the optical axis direction stepwise. The light transmitting member 74 is moved in the directions of arrows 86 and 88 by a driving device (not shown), and the position can be adjusted.
[0035]
  Light 38 guided from the light source 12 (see FIG. 1) enters the phase modulation device 32 and enters the light transmission member 74. The light incident on the light transmission member 74 travels through the light transmission member 74, exits the light transmission member 74 from the surface 76, and exits the phase modulation device 32 as light 90. The light transmitting member 74 has a refractive index N greater than 1.₀Therefore, the thickness dimension of the portion of the light transmitting member 74 through which the light 38 passes and {refractive index N₀-1.0 (refractive index of air)}, the optical path length of the light 38 is changed.
[0036]
  By moving the light transmitting member 74 in the direction of the arrow 86, the surface from which the light 38 exits the light transmitting member 74 can be set to one of the surfaces 78, 80, 82, 84. Thereby, the thickness dimension of the location of the light transmission member 74 through which the light 38 passes can be changed, and the optical path length of the light 38 can be adjusted.
[0037]
  With the phase modulation device 32 that can change such a phase difference, the phase difference between the object beam and the reference beam can be changed.
[0038]
  An exposure method for producing a hologram mask according to the present invention will be described with reference to FIG. The light 26 from the light source 12 is split into light 36 and 38 by the beam splitter 34. The light 36 passes through the reference light forming optical system 30 including the lenses 40 and 42 and enters the photosensitive material 20 of the hologram mask 18 as the reference light 28.
[0039]
  The light 38 enters the original mask 14 through the phase modulator 32, mirrors 44 and 46, and lenses 48 and 50. The light 16 transmitted through the original mask 14 is condensed as object light 22 by the condensing optical system 24 and imaged on or near the photosensitive material 20 of the hologram mask 18.
[0040]
  In this way, the two lights, that is, the object light 22 that has passed through the original mask 16 and the condensing optical system 24 and the reference light 28 that has not passed through the original mask 16 interfere with each other in the photosensitive material 20 or in the vicinity thereof, so The transmission shielding pattern is recorded as interference fringe information on the photosensitive material 20 of the hologram mask 18.
[0041]
  In the exposure, the light transmission shielding pattern of the light modulation layer formed on each of the original masks 14 is exposed to the photosensitive material 20 of the same hologram mask 18 by using a plurality of original masks 14 so that the light transmittance and the phase are related. A hologram mask 18 on which interference fringes including modulation information are formed is produced.
[0042]
  In the first exposure, the first object light 22 irradiated on the photosensitive material 20 through the first original mask 14 and the first reference light irradiated on the photosensitive material 20 without passing through the first original mask 14. 28 is used to expose the light-transmitting shielding pattern of the first original mask 14 onto the photosensitive material 20.
[0043]
  In the first exposure, the phase modulator 32 is in a certain state, which determines the phase difference between the object light and the reference light in the first exposure.
[0044]
  In the first exposure, the photosensitive material 20 has a latent image formed by a photochemical reaction in a region irradiated with light by the exposure.
[0045]
  In the second exposure subsequent to the first exposure, the photosensitive material 20 is irradiated without passing through the second object mask 22 and the second original mask 14 through the second original mask 14. The photosensitive material 20 is exposed to the light transmission shielding pattern of the second original mask 14 using the second reference light 28.
[0046]
  Prior to the second exposure, the phase modulation device 32 is operated so that the first phase difference between the first object light 22 and the first reference light 28, the second object light 22 and the second object light In order to change the second phase difference so that the second phase difference from the reference light 28 is different, the optical path length of the light 38 from the light source 12 through the beam splitter 34 is changed.
[0047]
  Accordingly, in the second exposure, light whose optical path length has been changed enters the second original mask 14 to become second object light and enters the photosensitive material 20. That is, the phase difference between the second object light 22 and the second reference light 28 depends on the amount of change in the optical path length generated in the optical path from the light source 12 to the photosensitive material 20 through the second original mask 14. Thus, the phase difference between the first object beam 22 and the first reference beam 28 is different.
[0048]
  The information recorded on the photosensitive material 20 by the first exposure includes information on the light transmission shielding pattern of the first original mask 14, and the information recorded on the photosensitive material 20 by the second exposure is the second original mask 14. The light transmission shielding pattern information and the phase modulation information are included. Information recorded on the photosensitive material 20 in the first exposure and information recorded on the photosensitive material 20 in the second exposure and including modulation information relating to the phase are recorded on the photosensitive material 20 by two exposures.
[0049]
  As described above, if a plurality of original masks are used, the same information as the information of the phase shift mask can be recorded on the hologram material, that is, the photosensitive material 20, without producing a difficult phase shift mask.
[0050]
  In the above description, the phase modulation device 32 that changes the phase difference is disposed in the optical path from the light source 12 through the original mask 14 to the photosensitive material 20 of the hologram mask 18, but the light source 12 passes through the original mask 14. For example, the optical path to the photosensitive material 20 of the hologram mask 18 is, for example, at the position indicated by numeral 52 in FIG.Original mask 14It may be arranged.
[0051]
  Further, the phase modulation device 32 is arranged in either of an optical path from the light source 12 through the original mask 14 to the photosensitive material 20 and an optical path from the light source 12 to the photosensitive material 20 without passing through the second original mask 14. May be.
[0052]
  Further, the object light with respect to the reference light 28 is different so that the diffraction efficiency due to the interference fringes formed on the photosensitive material 20 in the first exposure differs from the diffraction efficiency due to the interference fringes formed on the photosensitive material 20 in the second exposure. A light intensity reducing device for reducing the light intensity ratio of 22 on the light source 12 side from the original mask 14 may be provided so that the light intensity ratio of 22 differs between the first exposure and the second exposure.
[0053]
  The light intensity reducing device exposes the photosensitive material 20 so that the exposure amount given to the photosensitive material 20 is smaller than the exposure amount necessary to maximize the diffraction efficiency due to the interference fringes formed on the photosensitive material 20. An exposure adjustment device for adjusting the amount may be provided.
[0054]
  The photosensitive material 20 may be formed with the same photosensitive film or photosensitive layer that is used for both the first exposure and the second exposure. Further, the photosensitive material 20 may be formed with a different photosensitive film or photosensitive layer used for each of the first exposure and the second exposure.
[0055]
  In manufacturing the hologram mask 12, various apparatuses other than the above-described apparatus can be employed. For example, Junpei Kajiuchi, Physics Selection 22 “Holography” (1997), Manufactured apparatus based on the principle described in Shubobo, pp. 354-358, US Pat. No. 4,857,425 and US There is a manufacturing apparatus based on the method described in the specification of Japanese Patent No. 4,966,428. In the latter production apparatus, it is not necessary to provide a lens system between the hologram material and the original mask.
[0056]
  A hologram mask can also be produced using the exposure apparatus “HMA series” manufactured by Holtronic Technologies Limited of London, UK, which is the applicant of the above-mentioned US patent.
[0057]
  Specifically, a case where a hologram mask having a function similar to that of a Shibuya Levenson-type phase shift mask is manufactured will be described.
[0058]
  As shown in FIG. 3A, the Shibuya Levenson-type phase shift mask 92 includes a mask substrate 94, a light transmission part 96, a light shielding part 98, and a phase shifter 100. A phase shifter 100 is formed in a part of the light transmission parts 96. If the phase of the light that has passed through the light transmitting portion 96 that does not have the phase shifter 100 is used as a reference (phase 0), the light that has passed through the light transmitting portion 96 that has the phase shifter 100 changes by π (phase π). .
[0059]
  In order to produce a hologram mask having the same function as the Shibuya Levenson-type phase shift mask 92 by using the two original masks by the double exposure method, FIG.3The first original mask 102 shown in FIG.3The second original mask 104 shown in (c) is used.
[0060]
  The first original mask 102 includes a mask substrate 106, a light transmission part 108, and a light shielding part 110. The second original mask 104 includes a mask substrate 106, a light transmission part 112, and a light shielding part 114. The light transmitting portion 108 of the first original mask 102 corresponds to at least a part of the region shielded by the light shielding portion 114 of the second original mask 104.
[0061]
  In the embodiment shown in FIG. 3, the light transmitting portions 108 and 112 are formed in a strip shape having a predetermined width dimension and arranged in a striped pattern, and the one or more light shielding portions 110 and 114 are formed in a strip shape. Are disposed between the plurality of light transmission portions 108 and 112.
[0062]
  In the first exposure using the first original mask 102, the light transmission shielding of the first original mask 102 including the light transmission part 108 which is a transmission and phase 0 region corresponding to the light transmission part 96 of the phase shift mask 92. The pattern is exposed to the photosensitive material 20 of the hologram mask 18.
[0063]
  Subsequently, in the second exposure using the second original mask 104, a second light transmission portion 112 corresponding to the light transmission portion 96 having the phase shifter 100 of the phase shift mask 92 and a region of phase π is included. The light transmission shielding pattern of the original mask 104 is exposed to the photosensitive material 20 of the hologram mask 18. In the second exposure, the optical path length is changed by the phase modulation device 32 so that the phase of the light incident on the light transmission unit 112 is shifted by π as compared with the first exposure.
[0064]
  The phase difference between the object light and the reference light is changed in the second exposure by the phase modulation device 32, and information recorded on the photosensitive material 20 in the second exposure includes phase modulation information.
[0065]
  As another specific example, a case where a hologram mask having a function similar to that of a halftone phase shift mask is manufactured as a hologram mask will be described. In an exposure apparatus used for producing such a hologram mask, as will be described later, a light intensity reducing device (not shown) for reducing the light intensity ratio is disposed on the light source side from the original mask.
[0066]
  As shown in FIG. 4A, the halftone phase shift mask 116 includes a mask substrate 94, a light transmission portion 118, and a phase shifter 120. The phase shifter 120 is formed using a light semi-transmissive material having a predetermined transmittance. If the phase of the light passing through the light transmitting portion 118 is used as a reference (phase 0), the phase of the light passing through the phase shifter 120 is changed by π (phase π).
[0067]
  In order to produce a hologram mask having the same function as such a halftone phase shift mask 116 by a double exposure method using two original masks, the first original mask shown in FIG. 122 and a second original mask 124 shown in FIG.
[0068]
  The first original mask 122 includes a mask substrate 106, a light transmission part 126, and a light shielding part 128. The second original mask 124 includes a mask substrate 106, a light transmission part 130, and a light shielding part 132. The light transmitting portion 126 of the first original mask 122 corresponds to at least a part of the region shielded by the light shielding portion 132 of the second original mask 124.
[0069]
  In the embodiment shown in FIG. 4, the interference fringes finally formed on the photosensitive material 20 of the hologram mask 18 have alternating strip-like light transmissive portions and light semi-transmissive portions having a predetermined width dimension. Including interference fringes in the form of stripes. The light shielding portion 128 of the first original mask 122 corresponds to the light semi-transmissive portion of the striped interference fringe of the photosensitive material 20, and the light shielding portion 132 of the second original mask 124 is the stripe of the photosensitive material 20. This corresponds to the light-transmitting portion of the patterned interference fringes.
[0070]
  The light transmitting portion 126 of the first original mask 122 corresponds to at least a part of the region shielded by the light shielding portion 132 of the second original mask 124.
[0071]
  In the first exposure using the first original mask 122, the light transmission shielding of the first original mask 122 including the transmission corresponding to the light transmission part 118 of the phase shift mask 116 and the light transmission part 126 which becomes a phase 0 region. The pattern is exposed to the photosensitive material 20 of the hologram mask 18.
[0072]
  Subsequently, in the second exposure using the second original mask 124, the first light transmission part 130 including the light semi-transmissive and phase π regions corresponding to the light semi-transmissive phase shifter 120 of the phase shift mask 116 is included. The photosensitive material 20 of the hologram mask 18 is exposed to the light transmissive shielding pattern of the second original mask 124. In the second exposure, the optical path length is changed by the phase modulation device 32 so that the phase of the light incident on the light transmission unit 130 is shifted by π compared to the first exposure.
[0073]
  Further, in the second exposure, it is arranged on the light source 12 side from the second original mask 124 in the exposure apparatus so as to correspond to the transmittance of the light semi-transparent phase shifter 120 of the phase shift mask 116. The light intensity ratio is decreased by a light intensity reducing device (not shown).
[0074]
  As the light intensity reducing device, for example, a light absorption filter device can be used. Such a light absorption filter device includes a plurality of light absorption filters as an example, and reduces the intensity of light passing therethrough by appropriately moving at least one of the light absorption filters to the optical path. It may be a thing.
[0075]
  By such a light intensity reducing device, the diffraction efficiency due to the interference fringes formed on the photosensitive material 20 in the first exposure is different from the diffraction efficiency due to the interference fringes formed on the photosensitive material 20 in the second exposure. The light intensity ratio of the second object light to the second reference light is reduced.
[0076]
  The reduction of the light intensity ratio is to adjust the exposure amount given to the photosensitive material 20 so that the exposure amount given to the photosensitive material 20 of the hologram mask 18 becomes smaller than the exposure amount necessary to maximize the diffraction efficiency. Can also be done. The exposure amount given to the photosensitive material 20 is adjusted by adjusting the exposure time and the intensity of light from the light source.
[0077]
  A method for recording modulation information relating to light transmittance and phase on an object to be exposed by irradiating the hologram mask with light as described above will be described.
[0078]
  A recording apparatus 134 shown in FIG. 5 is an embodiment of a recording apparatus used in the recording method using the hologram mask according to the present invention, and other recording apparatuses may be used. The recording apparatus 134 uses an optical system similar to the optical system used in the exposure apparatus 10 shown in FIG.
[0079]
  The recording device 134 includes a light source 136, an irradiation optical system 138, and a condensing optical system 140.
[0080]
  The irradiation optical system 138 includes lenses 142 and 144, converts light 146 from the light source 136 into parallel light 148 and guides it to the photosensitive material 20 of the hologram mask 18. The irradiation optical system 138 is arranged in the recording device 134 so that the parallel light 148 is opposite to the reference light 28 at the time of recording on the hologram mask.
[0081]
  The condensing optical system 140 converts the light 150 that has passed through the hologram mask 18 into light 152, condenses it on the exposure object 154, and forms an image on the exposure object 154. The condensing optical system 140 is the same as the optical system 24 used when recording the hologram mask.
[0082]
  The “exposed object” includes “a semiconductor substrate on which a resist layer is formed”. Here, “semiconductor substrate” is used in the meaning of “base material on which a laminated region is formed”, and therefore includes a case where the base material is glass or the like. Further, at least “base material” is used to mean “a base material such as a circle or rectangle made of semiconductor or glass”, and “lamination region” means a region of layered material formed on the base material. Used, for example, includes a conductive layer such as a wiring or an electrode, a layer such as an electrical insulating material or a light selection material, a semiconductor layer, or the like.
[0083]
  Furthermore, the “object to be exposed” may be a substrate on which a light selection material for selecting a specific wavelength for producing a special illumination or illumination effect is laminated, and various changes can be made without departing from the gist thereof. .
[0084]
  When the information recorded on the photosensitive material 20 of the hologram mask 18 is recorded on the object to be exposed, the light 146 from the light source 136 enters the photosensitive material 20 of the hologram mask 18 via the irradiation optical system 138 including the lenses 142 and 144. Then, the light 150 that has passed through the hologram mask 18 is imaged on the object 154 by the condensing optical system 140.
[0085]
  At this time, since the same information as the information of the phase shift mask is recorded on the hologram material, that is, the photosensitive material 20, the resolution of the pattern to be formed is improved similarly to the effect of the phase shift mask.
[0086]
  The optical characteristics in the double exposure method as described above will be described below. A comparison between such a double exposure method and a one-time exposure method using a phase shift mask will also be described.
[0087]
  The amplitude distribution of the object light A formed through the first original mask used for the first exposure is represented by P_AThe complex amplitude distribution G of the light just before entering the hologram material, that is, the photosensitive material._AIs obtained by the following equation (1).
[0088]
[Expression 1]
  G_A= P_AXexp [iα] (1)
[0089]
  Here, α represents the phase of the object light A.
[0090]
  The amplitude distribution of the reference light R1 used for the first exposure is P_R1The complex amplitude distribution G of the light just before entering the hologram material_R1Is obtained by the following equation (2). γ₁Represents the phase of the reference beam R1.
[0091]
[Expression 2]
  G_R1= P_R1Xexp [iγ₁] (2)
[0092]
  The amplitude distribution of the object light B formed through the second original mask used for the second exposure is represented by P_BThe complex amplitude distribution G of the light just before entering the photosensitive material._BIs obtained by the following equation (3). β represents the phase of the object light B.
[Equation 3]
  G_B= P_BXexp [iβ] (3)
[0093]
  The amplitude distribution of the reference light R2 used for the second exposure is P_R2The complex amplitude distribution G of the light just before entering the hologram material_R2Is obtained by the following equation (4). γ₂Represents the phase of the reference beam R2.
[0094]
[Expression 4]
  G_R2= P_R2Xexp [iγ₂] (4)
[0095]
  Accordingly, the light intensity I given to the photosensitive material by the first exposure and the second exposure I_2ABIs obtained by the following equation (5).
[0096]
[Equation 5]
  I_2AB= | G_A+ G_R1｜²+ | G_B+ G_R2｜²
      = | G_A｜²+ | G_R1｜²+ G_A× G_R1 ^*+ G_A ^*× G_R1
        + | G_B｜²+ | G_R2｜²+ G_B× G_R2 ^*+ G_B ^*× G_R2. ... (5)
[0097]
  Where G_A ^*, G_B ^*, G_R1 ^*, G_R2 ^*Is G_A, G_B, G_R1, G_R2Represents the conjugate complex number of.
[0098]
  If the same reference light R is used as the reference light R1 used for the first exposure and the reference light R2 used for the second exposure, G_R1= G_R2= G_RThus, the equation (5) can be rewritten as the following equation (6).
[0099]
[Formula 6]
  I_2AB= | G_A+ G_R｜²+ | G_B+ G_R｜²
        = | G_A｜²+ | G_B｜²+ 2 × | G_R｜²
            + G_A× G_R ^*+ G_A ^*× G_R+ G_B× G_R ^*+ G_B ^*× G_R  ... (6)
[0100]
  Here, the amplitude distribution of the reference light R is expressed as P_RThe complex amplitude distribution G of the light just before entering the photosensitive material._RIs obtained by the following equation (7). γ represents the phase of the reference light R.
[0101]
[Expression 7]
  G_R= P_RXexp [iγ] (7)
[0102]
  After the exposure twice, the photosensitive material of the hologram mask is developed. When a material in which an intensity distribution is recorded as a transmittance distribution, such as a silver salt photosensitive material, is used as the photosensitive material, the amplitude transmittance distribution T recorded in the photosensitive material._2ABIs obtained by the following equation (8).
[0103]
[Equation 8]
  T_2AB= T₀+ T₁× I_2AB  ... (8)
[0104]
  Where T₀, T₁Is a constant determined by the type of photosensitive material used and the recording method on the photosensitive material.
[0105]
  After the development processing, information recorded on the photosensitive material is recorded on the object to be exposed. Light guided from the light source and incident on the photosensitive material, that is, illumination light R_LAs described above, when the above-described reference light R is used, the light irradiated on the object to be exposed, that is, the reproduction light S is expressed by the following formula (9) using formula (6), formula (7), and formula (8). It is calculated by.
[0106]
[Equation 9]
  S = G_R× T_2AB= G_R× (T₀+ T₁× I_2AB)
    = G_R× T₀+ G_RXt₁× {| G_A｜²+ | G_B｜²+ 2 × | G_R｜²}
          + T₁× (G_A× | G_R｜²+ G_A ^*× G_R ²)
          + T₁× (G_B× | G_R｜²+ G_B ^*× G_R ²(9)
[0107]
  In the equation (9), it can be understood as shown in the following equations (10-1), (10-2), and (10-3).
[0108]
[Expression 10]
  (0th order light) = G_R× T₀+ G_RXt₁× {| G_A｜²+ | G_B｜²+ 2 × | G_R｜²} (10-1)
  (± first order light of object light A) = t₁× (G_A× | G_R｜²+ G_A ^*× G_R ²(10-2)
  (± first order light of object light B) = t₁× (G_B× | G_R｜²+ G_B ^*× G_R ²(10-3)
[0109]
  Also, in the equation (9), the term t₁× (G_A× | G_R｜²) Represents the reproduction of the object light A, and the term t₁× (G_B× | G_R｜²) Represents the reproduction of the object light B.
[0110]
  As described above, in the double exposure method, a so-called noise term does not occur in the expression representing the reproduction light S. This means that unnecessary noise does not occur.
[0111]
  For comparison with the above-described double exposure method, a one-time exposure method using a phase shift mask will be described. In the one-time exposure using the phase shift mask, the object light A of the first exposure, the object light B of the second exposure, and the reference light R in the double exposure method are used for the photosensitive material in one exposure. Is irradiated.
  Therefore, the light intensity I given to the photosensitive material by only one exposure using the phase shift mask._1ABIs obtained by the following equation (11).
[0112]
## EQU11 ##
  I_1AB= | G_A+ G_B+ G_R｜²
        = | G_A｜²+ | G_B｜²+ | G_R｜²
            + G_A× G_B ^*+ G_A ^*× G_B
            + G_A× G_R ^*+ G_A ^*× G_R
            + G_B× G_R ^*+ G_B ^*× G_R  (11)
[0113]
  Amplitude transmittance distribution T recorded on the photosensitive material by one exposure._1ABIs obtained by the following equation (12).
[0114]
[Expression 12]
  T_1AB= T₀+ T₁× I_1AB  (12)
[0115]
  Light irradiated to the object to be exposed, that is, reproduction light S₁Is obtained by the following equation (13) using equations (7), (11), and (12).
[0116]
[Formula 13]
  S = G_R× T_1AB= G_R× (T₀+ T₁× I_1AB)
    = G_R× T₀+ G_RXt₁× {| G_A｜²+ | G_B｜²+ | G_R｜²}
          + G_RXt₁× (G_A× G_B ^*+ G_A ^*× G_B)
          + T₁× (G_A× | G_R｜²+ G_A ^*× G_R ²)
          + T₁× (G_B× | G_R｜²+ G_B ^*× G_R ²(13)
[0117]
  In the equation (13), it can be understood as shown in the following equations (14-1), (14-2), (14-3), and (14-4).
[0118]
[Expression 14]
  (0th order light) = G_R× T₀+ G_RXt₁× {| G_A｜²+ | G_B｜²+ | G_R｜²} (14-1)
  (Noise) = G_RXt₁× (G_A× G_B ^*+ G_A ^*× G_B(14-2)
  (± first order light of object light A) = t₁× (G_A× | G_R｜²+ G_A ^*× G_R ²) (14-3)
  (± first order light of object light B) = t₁× (G_B× | G_R｜²+ G_B ^*× G_R ²(14-4)
[0119]
  Also, in equation (14), the term t₁× (G_A× | G_R｜²) Represents the reproduction of the object light A, and the term t₁× (G_B× | G_R｜²) Represents the reproduction of the object light B.
[0120]
  As described above, in the one-time exposure using the phase shift mask, the reproduction light S₁A so-called noise term is generated in the equation representing. This means that unnecessary noise is generated. From this point, it can be understood that the method of the present invention has advantages over the conventional method.
[0121]
  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 relates to the present invention.Acts as a phase shift maskThe figure which shows the Example of the exposure apparatus for hologram mask preparation.
FIG. 2 relates to the present invention.Acts as a phase shift maskThe figure which shows the Example of the phase change apparatus used for the exposure apparatus for hologram mask manufacture. (A) is a figure which shows the phase change apparatus using a corner cube, (b) is a figure which shows the phase change apparatus using a light transmissive member.
FIG. 3 relates to the present invention.Acts as a phase shift maskThe figure for demonstrating the Example of the exposure method for hologram mask preparation. (A) is a figure which shows a phase shift mask, (b) is a figure which shows a 1st original mask and a hologram mask, (c) is a figure which shows a 2nd original mask and a hologram mask.
FIG. 4 relates to the present invention.Acts as a phase shift maskThe figure for demonstrating the other Example of the exposure method for hologram mask preparation. (A) is a figure which shows a phase shift mask, (b) is a figure which shows a 1st original mask and a hologram mask, (c) is a figure which shows a 2nd original mask and a hologram mask.
FIG. 5 is a diagram showing an example of a recording apparatus used in an embodiment of a recording method using a hologram mask according to the present invention.
[Explanation of symbols]
  10 Exposure equipment(Production equipment)
  12, 136 light source
  14 Original mask
  18 Hologram mask (createdPhase shift mask)
  20 Photosensitive materials
  22 Object light
  24, 140 Condensing optical system
  28 Reference beam
  30 Reference light forming optical system
  32 Phase modulator
  34 Beam splitter
  54 First reflection mirror
  56 corner cube
  58 Second reflection mirror
  74 Light transmission member
  102, 122 first original mask
  104, 124 Second original mask
  106 Mask substrate
  108, 112, 126, 130 Light transmission part
  110, 114, 128, 132 Light shielding part
  134 Recording device
  138 Irradiation optical system
  154 Object to be exposed

Claims (12)

A method of creating a phase shift mask having phase modulation information including at least two types of phase value regions,
Providing at least two types of original masks corresponding to the regions of the respective phase values;
Using the first object light irradiated on the hologram material through the first original mask and the first reference light irradiated on the hologram material without passing through the first original mask, A first exposure step of exposing the hologram material to a light transmission shielding pattern of one original mask;
Using the second object light irradiated on the hologram material through the second original mask and the second reference light irradiated on the hologram material without passing through the second original mask, A second exposure step of exposing the hologram material to the light transmission shielding pattern of the original mask of 2;
The first phase difference between the first object light and the first reference light is different from the second phase difference between the second object light and the second reference light. A method for producing a phase shift mask characterized by the above. A method of creating a phase shift mask having phase modulation information including at least two types of phase value regions,
Preparing at least a first original mask and a second original mask corresponding to each phase value region;
Using the first object light irradiated on the hologram material through the first original mask and the first reference light irradiated on the hologram material without passing through the first original mask, A first exposure step of exposing the hologram material to a light transmission shielding pattern of one original mask;
Using a second object beam irradiated on the hologram material through the second original mask and a second reference light irradiated on the hologram material without passing through the second original mask, from a light source The first phase difference between the first object light and the first reference light, the second object light, and the second reference light at any position on the optical path to the hologram material. A second exposure step of changing the second phase difference so that the second phase difference between the first and second masks is different and exposing the light transmission shielding pattern of the second original mask to the hologram material; A method for producing a phase shift mask, comprising:  3. The method for producing a phase shift mask according to claim 1, wherein the first exposure step and the second exposure step are second exposure steps subsequent to the first exposure step. 4.  4. The method of creating a phase shift mask according to claim 1, wherein the reference light in the first exposure step and the second exposure step is generated by the same reference light optical system. 5. .  5. The method of creating a phase shift mask according to claim 1, wherein the phase modulation information of the phase shift mask has two kinds of phase values different from each other by π. 6.  The step of changing the phase difference includes at least one of an optical path from the light source through the second original mask to the hologram material and an optical path from the light source to the hologram material without passing through the second original mask. The method for producing a phase shift mask according to claim 2, further comprising a step of changing the length. The light transmission shielding pattern is a strip-shaped light transmission portion having a predetermined width dimension, and a plurality of light transmission portions arranged in a striped pattern, and a plurality of band-shaped light transmission portions arranged between the plurality of light transmission portions. Including a light shielding part,
The light transmitting portion of the first original mask corresponds to at least a part of a region shielded by the light shielding portion of the second original mask;
The method for producing a phase shift mask according to claim 1, wherein a difference between the first phase difference and the second phase difference is approximately π.   The difference between the diffraction efficiency due to the first interference fringes formed on the hologram material in the first exposure step and the diffraction efficiency due to the second interference fringes formed on the hologram material in the second exposure step. The method for producing a phase shift mask according to claim 1, further comprising a diffraction efficiency changing step for generating the same.   The diffraction efficiency changing step reduces the light intensity of the object light with respect to the reference light on the light source side from the original mask so that the light intensity ratio of the object light is smaller than a light intensity ratio necessary for maximizing the diffraction efficiency. The method of producing a phase shift mask according to claim 8, further comprising an exposure amount adjustment step of adjusting an exposure amount applied to the hologram material so as to be smaller than an exposure amount necessary to maximize the diffraction efficiency.   The method for producing a phase shift mask according to any one of claims 1 to 9, wherein the hologram material is formed with the same photosensitive film or photosensitive layer used in both the first exposure step and the second exposure step. .   The phase shift according to any one of claims 1 to 9, wherein the hologram material is formed with different photosensitive films or photosensitive layers used in the first exposure step and the second exposure step, respectively. How to create a mask. A phase shift mask creating apparatus for creating a phase shift mask having phase modulation information,
A light source;
An optical system of object light that is incident on the hologram material as light from the light source through the original mask,
An optical system of reference light in which light from the light source enters the hologram material as reference light without passing through the original mask;
An apparatus for producing a phase shift mask, comprising: phase modulation means provided in at least one of the optical system of the object light and the optical system of the reference light.

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